The conserved amino-terminal domain of hSRP1α is essential for nuclear protein import

Karsten Weis, Ursula Ryder, Angus I. Lamond

    Research output: Contribution to journalArticlepeer-review

    224 Citations (Scopus)


    Nuclear proteins are targeted through the nuclear pore complex (NPC) in an energy-dependent reaction. The import reaction is mediated by nuclear localization sequences (NLS) in the substrate which are recognized by heterodimeric cytoplasmic receptors. hSRP1α is an NLS-binding subunit of the human NLS receptor complex and is complexed in vivo with a second subunit of 97 kDa (p97). We show here that a short aminoterminal domain in hSRP1α is necessary and sufficient for its interaction with p97. This domain is conserved in other SRP1-like proteins and its fusion to a cytoplasmic reporter protein is sufficient to promote complete nuclear import, circumventing the usual requirement for an NLS receptor interaction. The same aminoterminal domain inhibits import of NLS-containing proteins when added to an in vitro nuclear transport assay. While full-length hSRP1α is able to leave the nucleus, the amino-terminal domain alone is not sufficient to promote exit. We conclude that hSRP1α functions as an adaptor to tether NLS-containing substrates to the protein import machinery.

    Original languageEnglish
    Pages (from-to)1818-1825
    Number of pages8
    JournalEMBO Journal
    Issue number8
    Publication statusPublished - 15 Apr 1996


    • hSRP1α
    • NLS
    • Nuclear import
    • Nuclear localization signals
    • Protein transport

    ASJC Scopus subject areas

    • Neuroscience(all)
    • Molecular Biology
    • Biochemistry, Genetics and Molecular Biology(all)
    • Immunology and Microbiology(all)


    Dive into the research topics of 'The conserved amino-terminal domain of hSRP1α is essential for nuclear protein import'. Together they form a unique fingerprint.

    Cite this